Meningitis Flashcards
What is meningitis?
Inflammation of the leptomeninges and underlying subarachnoid CSF
What ages are more predisposed to meningitis?
Infants, young children and the elderly
What is the underlying cause of most cases of meningitis?
An infectious agent that has colonised or established a localised infection elsewhere in the host and spread to the CNS
What sites of infections are commonly associated with meningitis?
- Skin
- Nasopharynx
- Respiratory tract
- GI tract
- GU tract
How can an infectious organism at a distant site cause meningitis?
By circumventing the hosts defense and gaining access to the CNS
How might bacteria gain access to the CNS to cause meningeal disease?
- Invasion of blood stream and haematogenous seeding
- Retrograde neuronal pathway e.g. olfactory or peripheral nerves
- Direct contiguous spread
In what conditions might organisms directly spread to cause meningeal disease?
- Sinusitis
- Otitis media
- Congenital malformations
- Trauma
What can often worsen the problem in meningitis?
The immune response
How can the immune response worsen meningitis?
Creates leaky blood vessels, allowing fluid and WBC to enter meninges and cause swelling
What is the result of swelling in meningitis?
Decreased blood flow to the brain
What can cause inflammation of the meninges?
- Viruses
- Bacteria
- Other micro-organisms
- Non-infective causes
What is the more common form of meningitis?
Viral
What is the more serious form of meningitis?
Bacterial
Due to the severity of bacterial meningitis, what should happen to all patients?
Treat as bacterial meningitis until proven otherwise
What viruses can cause meningitis?
- Enterovirus
- HSV (generally type 2)
- VZV
- Mumps
- HIV
What are the most common bacterial causes of meningitis in neonates?
- GBS
- Listeria monocytogenes
- E. coli
What are the most common bacterial causes of meningitis in infants?
- H. Influenzae type B
- Nisseria meningitides
- Strep. pneumonia
What group of infants are at risk of H. influenza B meningitis?
Those who are unvaccinated
What are the most common bacterial causes of meningitis in adults?
- Strep. pneumoniae
- H. influenza B
- N. meningitidis
- Gram -ve bacilli
- Staphylococci
- Streptococci
- L. monocytogenes
What are the most common bacterial causes of meningitis in the elderly and immunocompromised?
- Klebsiella pneumoniae
- E. coli
- Pseudomonas aeruginosa
- Staph aureus
What are the non-infective causes of meningitis?
- Malignant cells e.g. leukamia and lymphoma
- Chemicals e.g. intrathecal drugs
- Drugs e.g. NSAIDs, trimethoprim
- Sarcoidosis
- SLE
What are the risk factors for meningitis?
- CSF shunts
- Dural defects
- Spinal procedures
- DM
- Alcoholism
- Bacterial endocarditis
- IV drug use
- Adrenal insufficiency
- Malignancy
- CF
- Crowding e.g. students
What are the possible presenting features of meningitis?
- Fever
- Headaches
- Neck stiffness
- Photophobia
- Signs of shock
- Kernig’s sign
- Brudzinksi’s sign
- Paresis and focal neurological defecits
- Seizures
What are the signs of shock?
- Tachycardia
- Respiratory distress
- Poor urine output
What is Kernig’s sign?
Pain and resistance on passive knee extension with hips fully flexed
What is Brudzinksi’s sign?
Hips flex on bending the head forward
How may viral meningitis be distinguished from bacterial meningitis?
Often indistinguishable but can be more mild
In what age groups are the classical symptoms of meningitis often not seen?
Infants and the elderly
Are investigations used in meningitis?
Yes but should not delay treatment
What investigations may be useful in meningitis?
- LP
- Renal function testing
- Coagulation
- MRI
- CT
- CXR
When should an LP be performed in suspected meningitis?
Immediately if no signs of raised ICP or focal neurology
What tests should CSF undergo in suspected meningitis?
- Gram stain
- Ziehl-Neelsen stain
- Cytology
- Virology
- Glucose
- Protein
- Culture
- Rapid antigen screen
What can MRI be useful for in meningitis?
Detecting and monitoring complications of meningitis
What is CT reserved for in meningitis?
Specific adverse clinical features
When might a CXR be useful in suspected meningitis?
To look for lung abscess in suspected TB
What are the potential differentials for meningitis?
- Other causes of pyrexia and infection
- Intracranial abscess
- Other causes of altered mental state and coma
What are some examples of other conditions that can cause altered mental state and coma?
- Encephalitis
- Subarachnoid haemorrhage
- Brain tumours
What are the three main principals of general meningitis treatment?
- Supportive treatment
- Treatment of infection (or other underlying cause)
- Treat complications
How is viral meningitis managed?
Supportive therapy with analgesia, nutritional support, hydration and oxygenation
When can specific management be given in viral meningitis?
When the causative organism is known
What antiviral can be used in herpetic meningitis?
Aciclovir
When is aciclovir effective in treating herpetic meningitis?
If given early in the course of the infection
When should IV aciclovir be given if evidence of herpes simplex encephalitis?
Immediately
What can be given in CMV meningitis?
Ganciclovir
Why is close monitoring required for patients on ganciclovir?
It has significant renal toxicity
What specific management is given in enterovirus meningitis?
None - it is usually self limiting
What should be done if a patient is suspected to have bacterial meningitis in primary care?
Rapid transfer to secondary care (999)
What should patients in primary care with suspected meningitis be given before transfer if there is a non-blanching rash?
IM or IV benzylpenicllin
What makes up secondary care management of bacterial meningitis?
Supportive treatment and antibiotic therapy
How should immediate antibiotic therapy in bacterial meningitis be determined?
Empirical antibiotics
Once immediate antibiotic therapy for bacterial meningitis has been started how can changes to the antibiotic of choice be guided?
By microbiological diagnosis
What is usually the empirical antibiotic of choice in bacterial meningitis?
IV ceftriaxone
What is the antibiotic of choice for proven meningococcal meningitis?
IV ceftriaxone for at least 7 days
What is usually the antibiotic of choice for proven pneumococcal meningitis?
Vancomycin and 3rd-gen cephalosporin (e.g. ceftriaxone or cefataxime)
What is the antibiotic of choice for proven H. influenzae type B meningitis?
IV ceftriaxone for 10 days
What is the antibiotic of choice for proven GBS meningitis?
IV cefotaxime for at least 14 days
What is the antibiotic of choice for proven Listeriosis meningitis?
IV amoxicillin or ampicillin for 21 days + gentamicin for at least first 7 days
If a case of bacterial meningitis is confirmed in secondary care what must be done by primary care?
Involvement in identifying contacts who are at risk
What should be given to contacts who are at risk of bacterial meningitis?
Prophylactic antibiotics
Should antibiotics be given to contacts who are not at risk of bacterial meningitis?
No, reassure only
When should prophylaxis be considered (i.e when is a contact at risk) in contacts of a patient with bacterial meningitis?
In people who had prolonged close contact with the case in a house-hold type setting during 7 days before onset of illness
In what time frame should prophylactic antibiotics be given for bacterial meningitis?
ASAP and within 24 hours of diagnosis of the index case
Why is bacterial meningitis important from a public health perspective?
It is a notifiable disease in England and Wales
What vaccinations are available to protect against causes of meningitis?
- Meningitis B
- 6-in-1 vaccines
- Pneumococcal vaccine
- Hib/MenC vaccine
- MMR vaccine
- Men ACWY
What does the Men B vaccine protect against?
Meningococcal group B
When is the Men B vaccine and its boosters given?
- 8 weeks
- 16 weeks
- 1 year
What does the 6-in-1 vaccine contain protection against?
Haemophilus influenzae type B
When is the 6-in-1 vaccine given?
- 8 weeks
- 12 weeks
- 16 weeks
When is the pneumococcal vaccine given?
- 8 weeks
- 16 weeks
- 1 year
What does the Hib/MenC vaccine protect against
Haemophilus influenzae type B and Menigococcal group C
When is the Hib/MenC vaccine given?
1 year
What does the MMR vaccine protect against?
Measles, mumps and rubella
Why is the MMR vaccine relevant in preventing meningitis?
It is sometimes a complication of measles, mumps or rubella
When is the MMR vaccine given?
- 1 year
- 3 years and 4 months
What does Men ACWY protect against?
Meningococcal groups ACWY
When is the Men ACWY vaccine given?
To teenagers and first time university students
What are the early complications of meningitis?
- Septic shock
- Septic arthritis
- Pericardial effusion
- Haemolytic anaemia
- Subdural effusion
- SIADH
- Seizures
What can result from septic shock caused by meningitis?
- DIC
- Coma
- Cerebral oedema
- Raised ICP
What are the delayed complications of meningitis?
- Hearing impairment
- Cranial nerve dysfunction
- Multiple seizures
- Focal paralysis
- Subdural effusions
- Hydrocephalus
- Intellectual deficits
- Ataxia
- Blindness
